I think it's important to divide "preparation" into two categories: equipment and mental/emotional.
First and foremost, the equipment needs to be ready. That means everything organized, lenses clean, batteries charged, film/cards packed and ready, and all the small extras such as meters, cable releases, levels, loupes, pocket knives, flashlights, reading glasses (sad, but true!), etc. in their assigned pockets. Having our equipment prepared and ready is necessary to allow us to concentrate on the subject at hand rather than equipment issues. Nothing is more frustrating than being unable to quickly locate a piece of needed gear when a great photo opp presents itself. We're not all going to be as lucky as AA with is Hernandez moonrise shot, for which he couldn't find his light meter and had to estimate exposure.
Mental/emotional preparation, on the other hand, is going to be unique to each photographer's personality and style. Unlike the author, I would never even consider sitting around a kitchen table listening to music and thumbing through photo books before a planned outing. That's not my style. I just go. It works...for me.
My emotional and mental preparation, if needed, usually happens on site, either at a found situation or a planned destination. Deep breaths, eyes closed (for few minutes), trying to free my mind of the over abundance of objective distractions (work, lawn mowing, etc) and commune with the subject. At times, if a scene is fleeting or perhaps overly compelling, I skip the foreplay and head straight into shooting mode. It all depends.
The bottom line is, at least for me, preparation starts with equipment. That's the foundation. The constant. Preparing my heart and mind, on the other hand, is an ebbing and flowing process which changes with each shoot. Works for me.